1. Field of the Invention
The present invention relates to a mixing apparatus having an automatic delay correction capability of automatically adjusting delay time in order to eliminate time differences among a plurality of input signals.
2. Description of the Related Art
Conventionally, there is a known mixing apparatus which mixes tones collected by a multiplicity of microphones and transmits the mixed tones to power amplifiers and various recoding apparatuses or transmits the mixed tones to effectors and players playing music (see Japanese Unexamined Patent Publication No. 2005-252328, for example). By manipulating operating elements, an operator who manipulates the mixing apparatus controls the tone volume or the timbre of tones of musical instruments or singing voices collected by the microphones so that the musical performance will be expressed most appropriately. The mixing apparatus has a plurality of input channels, a mix bus for mixing signals input from the input channels, and an output channel for outputting the mixed signals. The respective input channels control the frequency characteristic (the frequency response characteristic), the mixing level and the like of input signals before outputting the controlled signals to the mix bus, whereas the mix bus mixes supplied signals and then outputs the mixed signals to the output channel. The output channel controls the level and the like of the mixed signals input from the mix bus and then outputs the controlled signals.
In the conventional mixing apparatus, an audio processing portion of each input channel controls the level and the frequency characteristic of input signals. The audio processing portion has a delay means, so that input signals are delayed by a certain period of time by the delay means. The reason why input signals are delayed by the delay means is because the input signals which are the signals of a tone collected by microphones have time differences among the input signals depending on respective differences in distance between a tone generator and respective locations of the microphones, so that the mixing of the input signals without delay may cause ill effect on the quality of tones due to the phase shifts caused by the time differences in the input signals. By adjusting respective delay times set for the respective delay means among the respective input channels, therefore, the conventional mixing apparatus eliminates the time differences in input signals among the input channels so that the signals will be in phase with each other.
Although the conventional mixing apparatus is provided with the delay means for each input channel in order to adjust the phase of input signals, the user has to manually specify respective delay times for the input channels while listening to mixed tones. Therefore, the conventional mixing apparatus is disadvantageous in that in a case where there are a multiplicity of input channels, the user is required to follow complicated and time-consuming procedures of specifying delay times for the respective input channels in order to adjust delay times for the respective input channels. In addition, there is a disadvantage that it is difficult for the user to adjust the delay times so that input signals will be in phase with each other.